Methane: emissions increase and it's not a good news

August 27, 2020

It is the second greenhouse gas with even a global warming potential larger than CO2. An international study realized in the framework of the Global Carbon Project provides updated information and data on its increasing concentrations in the atmosphere. Eyes on many sectors, such as agriculture, waste and fossil fuel sectors. Among the authors, CMCC researchers Simona Castaldi and Sergio Noce.

Not only CO2. Of course, carbon dioxide plays a key role in global warming, but among all the greenhouse gases, methane deserves a special attention because of its larger global warming potential (28 times higher than carbon dioxide on a 100-year time horizon). Moreover, once in the atmosphere carbon dioxide can continue to affect climate for thousands of years. Methane, by contrast, is mostly removed from the atmosphere by chemical reactions, persisting for about 12 years. Thus, although methane is a potent greenhouse gas, its effect is relatively short-lived and any measures to remove methane emissions from the atmosphere can have a very rapid positive effect.
Methane is therefore becoming an increasingly important component for managing realistic pathways to mitigate climate change.
After a period of stabilizations in the early 2000s, methane concentrations are rising again since 2007. The increase in methane concentrations follows trends of future scenarios that do not comply with the objectives of Paris Agreement.

This is the trend underlined in a study recently published on Earth System Science Data (among the authors, the CMCC researchers Simona Castaldi and Sergio Noce from IAFES – Impacts on Agriculture, Forests and Ecosystem Services Division), complemented by an article in Environmental Research Letters. The study was conducted by an international research team and led by the Laboratoire des Sciences du Climat et de l'Environnement (LSCE, CEA-CNRS-UVSQ) in France, under the umbrella of the Global Carbon Project that initiated the work. It represents an up-date of the global methane sources and sinks to the atmosphere for the period 2000-2017. This budget show that global methane emissions have increased by 9 % (about 50 Million tons) between 2000-2006 and 2017. Anthropogenic emissions appear to be the main contributors to this increase, with equal shares between fossil fuel sector and agriculture and waste sector.
"We know well", commented CMCC researchers Simona Castaldi and Sergio Noce, "that carbon dioxide is the major driver of climate change, but methane has undoubtedly an important role in this process. This study recently published on ESSD is the result of the great effort of an international research team of more than 90 co-authors; it represents an update of a research previously published in 2016 summing up our current knowledge on methane emissions, their trends and evolution, while combining knowledge of more than 70 research centers all around the world. Each researcher gave a contribution according to her/his own expertise: at the CMCC we dealt with an estimate of CH4 emissions from termites at the global scale – CH4 is released during the anaerobic decomposition of plant biomass in their gut -."

A likely major driver of the recent rapid rise in global CH4 concentrations is an increase of emissions mostly from agriculture and waste management; anthropogenic emissions are shared as follows between the different main sources of methane: 30% from enteric fermentation and manure management; 22% from oil and gas production and use; 18% from handling solid and liquid wastes; 11% from coal extraction; 8% from rice cultivation; 8% from biomass and biofuel burning. The rest is attributed to transport (e.g. road transport) and industry.
64% of global methane emissions originate from the Tropics, 32 % from the Northern mid-latitudes and only 4% from the Northern high latitudes.
Therefore, methane emissions from boreal regions did not increased significantly. This means that the high climate sensitivity of boreal regions does not (yet) translate in large increase in methane emissions.

Increasing emissions in Africa, Asia and North America
The three main regions contributing to this methane emission increase are likely: Africa, China and Asia, each contributing 10-15 million tons of CH4. Then North America likely contribute to 5-7 million tons, including 4-5 million tons from USA.
In Africa and Asia (except China), the agriculture and waste sector contribute the most, followed by the fossil fuel sector. This is the opposite for China and North America, where the increase in the fossil fuel sector is largest than the one in the agriculture and waste sector.

Decreasing emissions in Europe
Europe seems to be the only region where emissions have decreased: between -4 et -2 million tons, depending on the approach used for the estimation. This decrease is mainly related to the agriculture and waste sector.

To meet the objectives of Paris Agreement, not only CO2 emissions need to be reduced but also methane emissions.
Despite still some uncertainties in methane sources and sinks, the recent increase in methane concentrations suggests a dominant anthropogenic contribution.
Although methane is a potent greenhouse gas, its effect is relatively short, remaining in the atmosphere for about 10 years, and reducing methane emissions would have a rapid positive effect on climate.
Methane therefore might offer growing opportunities for climate change mitigation while providing rapid climate benefits and economic, health and agricultural co-benefits.

The LSCE press release, based on the following publications:

Saunois et al. (2020) The Global Methane Budget 2000-2017. Earth System Science Data.

Jackson et al. (2020). Increasing anthropogenic methane emissions arise equally from agricultural and fossil fuel sources. Environmental Research Letters.

Access to the data:
Data for the global methane budget are available from the Global Carbon Atlas, with budgets by regions and sectors. For the release of the global methane budget, the Global Carbon Atlas includes a new design and new applications related to the Global Carbon Project: CO2 emissions for 343 cities worldwide, and carbon cycle and natural CO2 emissions from rivers and lakes.

Data and figures:

CMCC Foundation - Euro-Mediterranean Center on Climate Change

Related Climate Change Articles from Brightsurf:

Are climate scientists being too cautious when linking extreme weather to climate change?
Climate science has focused on avoiding false alarms when linking extreme events to climate change.

Mysterious climate change
New research findings underline the crucial role that sea ice throughout the Southern Ocean played for atmospheric CO2 in times of rapid climate change in the past.

Mapping the path of climate change
Predicting a major transition, such as climate change, is extremely difficult, but the probabilistic framework developed by the authors is the first step in identifying the path between a shift in two environmental states.

Small change for climate change: Time to increase research funding to save the world
A new study shows that there is a huge disproportion in the level of funding for social science research into the greatest challenge in combating global warming -- how to get individuals and societies to overcome ingrained human habits to make the changes necessary to mitigate climate change.

Sub-national 'climate clubs' could offer key to combating climate change
'Climate clubs' offering membership for sub-national states, in addition to just countries, could speed up progress towards a globally harmonized climate change policy, which in turn offers a way to achieve stronger climate policies in all countries.

Review of Chinese atmospheric science research over the past 70 years: Climate and climate change
Over the past 70 years since the foundation of the People's Republic of China, Chinese scientists have made great contributions to various fields in the research of atmospheric sciences, which attracted worldwide attention.

A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.

Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).

Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.

Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.

Read More: Climate Change News and Climate Change Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to